The eye of a human or animal is subject to the irreversible malfunctioning that occurs, for example, when the lens of the eye experiences permanent lens clouding, also known as a cataract condition. A well known surgical procedure for restoring vision impaired by lens clouding or other such aberration involves removal of the natural lens and replacement thereof with an artificial intraocular lens, commonly referred to as an IOL.
Early IOL's utilized lenses made of rigid material and having diameters ranging from six millimeters to eight millimeters, necessitating a commensurately large ocular incision for emplacement. More recent developments in IOL technology have made available flexible artificial lenses which are capable of being deformed by bending, squeezing or rolling to achieve a smaller size prior to insertion. This deformation of the lens prior to insertion allows the size of the associated incision to be significantly reduced to a length on the order of three millimeters. As a result of such shortening of the ocular incision, surgical trauma to the eye and the associated problems of post-operative astigmatism and prolonged healing time are substantially lessened.
For some years flexible lenses have been deformed by hand, utilizing forceps to fold or bend the lenses prior to insertion in the eye. To minimize the risk of scratching of the lenses as well as to reduce the physical difficulty inherent in such manual deformation techniques, a number of lens inserting devices have been developed. Among these is the apparatus disclosed in U.S. Pat. No. 4,834,09 (Patton) which utilizes a retractable sleeve to deform a flexible lens holder. Alternative devices are disclosed by U.S. Pat. No. 4,862,363 (Cummings), wherein the lens is collapsed between the two jaws of a holder, and in U.S. Pat. No. 4,934,363 (Smith), wherein an external paddle folds the lens as the flexible paddle is retracted into a rigid tube.
While each of these devices avoids some of the problems attendant to lens manipulation with forceps, each carries with it its own drawbacks. For example, the invention of U.S. Pat. No. 4,934,363 employs an elaborate and expensive drive mechanism to advance the lens through the holder; the invention of U.S. Pat. No. 4,862,885 utilizes complex ratchet and pawl operation to deform the lens; and the invention of U.S. Pat. No. 4,934,363 requires a membrane to be inserted into the eye along with the lens and then withdrawn from the eye, a process that not only introduces an extraneous object into the delicate surgical site, but adds a step the surgeon must perform to retrieve the membrane after lens implantation.
Additionally, these conventional insertion methods and devices carry the further drawbacks of potentially scratching the central light-focusing portion, or optic, of the lens, and of damaging the delicate lens haptics or fixation members. Haptics, which hold the optic in place after the lens is inserted into the eye, typically take the form of a radial flange that surrounds the lens optic, or of generally radially projecting filaments of various configurations (J-shaped or C-shaped, for example) extending in pairs from near the periphery of the optic. If a haptic is damaged during lens insertion, the incision may have to be enlarged to permit removal of the damaged lens, thus negating the advantages of the smaller initial incision.
Surgeons who have used existing lens insertion devices have expressed (see e.g., J. Cataract Refract Surg., March 1992, P.206) that a preferred instrument would provide (1) reliable and safe release of the IOL into the eye, (2) minimal incision enlargement, and (3) ease of loading the IOL into the instrument. Also mentioned frequently as a desirable goal is freedom from damage to the lens optic and haptics. Further, some previous insertion devices have been designed to manipulate only the radial flange configuration of intraocular lens: an apparatus that operates well with both configurations, preparing both flange and loop haptic lenses for insertion with negligible distortion to the lens optic, would be desirable.
Accordingly, it is an object of this invention to provide a simplified, easy to operate device which combines in one instrument the functions of preparing a flexible intraocular lens for insertion through a small incision and of inserting the lens into the eye, eliminating the need for pre-folding or manipulating the lens outside the device.
A further object of the present invention is to provide a simple and inexpensive method of quickly and sequentially curling and inserting an intraocular lens through a small incision so that manual handling of the lens is minimized and permanent deformation of the lens is avoided.
A still further object is to provide an instrument that will safely accommodate and implant flexible intraocular lenses with both flange and loop haptic members.